As a sensor element used in a magnetometric sensor, and the like, a magneto-impedance sensor element, which uses a magneto-sensitive body capable of changing its properties depending on an external magnetic field (hereinafter may be sometimes referred to as “MI sensor element”), are known (see Patent Documents 1 and 2 below).
As shown in FIG. 14, an MI sensor element 91 contains a substrate 94 formed of a non-magnetic material, a magneto-sensitive body 92 which is fixed on the substrate 94 and is formed of the amorphous material, and a detecting coil 93 which is wound around the magneto-sensitive body 92 through an insulator 95.
When a pulse current or a high-frequency current is made to flow into the magneto-sensitive body 92, a voltage corresponding to a magnetic field strength acting on the magneto-sensitive body 92 is output from the detecting coil 93. The magnetic field strength can be detected by measuring this voltage.
In addition, as shown in FIGS. 15 and 16, the MI sensor element 91 is also known which includes a plurality of magneto-sensitive bodies 92 and detecting coils 93 connected in series or in parallel (See Patent Document 1). When detecting coils 93 are connected in series, the strong magnetic field can be detected, and the MI sensor element 91 having a high output voltage can be obtained. In addition, a connection of detecting coils 93 in parallel can decrease a noise generated in the detecting coil 93.